The present invention relates to filler tube assemblies for fuel tanks and particularly fuel tanks employed on passenger car and light truck vehicles. Such fuel tanks and fuel systems for motor vehicles have recently become subject to mandated requirements limiting fuel vapor emissions into the atmosphere. In addition, it has more recently been required to provide a vehicle on-board diagnostic system to detect leakage of fuel vapors from the tank and fuel system during periods of engine inoperation. The on-board diagnostics (OBDII) requires a slight vacuum or positive pressurization within the tank to conduct the leak test; and, therefore, the entire fuel system including the tank filler tube or neck must be capable of being tightly sealed.
The requirement that the fuel system including the tank and the filler neck be tightly sealed to prevent vapor emission to the atmosphere and enable diagnostic testing with a slight pressure difference from atmospheric in the tank has resulted in problems in manufacturing the fuel tank and filler, inasmuch as the filler tube cap has been found to be a source of leakage when improperly replaced or insufficiently tightened after refueling. Thus, it has been desired to provide a way or means of eliminating the filler tube cap on motor vehicle fuel tank systems and yet provide for refueling with a conventional dispensing nozzle and to provide closure upon the nozzle removal in a manner that ensures vapor tight sealing.
Heretofore, proposals for capless filler tubes for motor vehicle fuel tanks have been complicated, bulky, difficult to manufacture and assemble in the vehicle and consequently relatively high in cost. Thus, it has long been desired to provide a simple relatively low cost and easy to manufacture and assemble a capless closure and filler tube for a motor vehicle fuel tank which provides adequate vapor-tight sealing after refueling.